Place the drawer inside the cabinet and mark on the front edge where the interior slides (those already installed inside the cabinet) are.
Use a level to level up the front of the drawer before marking the opposite side.
Measure from the bottom edge of the side of the drawer to where the slider should be placed. Mark this measurement at intervals along the drawer's length. This applies to any style in which sliders are side mounted.
Measure and mark the opposite side using the same measurement. Measure carefully and accurately or your drawer will end up crooked and will not function properly.
Use the appropriate screws and a drill fit with an appropriate bit to attach the sliders to the drawer. Be sure your screws are the right length.